Material aluminum alloy, qq-a-3556, 245-t; surface treatment black alumilite, cl 1; o/a diameter 0.468 in.; o/a thk 0.0641 in.; 4 slots at 90 degrees angles 0.0625 to 0.0635 in. W and 0.064 in. Deep; finish smooth on inside sides of slots and front and back of disk
